Function kqueue_drain

freebsd/kern/kern_event.c:2083–2144

}

static void
kqueue_drain(struct kqueue *kq, struct thread *td)
{
	struct knote *kn;
	int i;

	KQ_LOCK(kq);

	KASSERT((kq->kq_state & KQ_CLOSING) != KQ_CLOSING,
	    ("kqueue already closing"));
	kq->kq_state |= KQ_CLOSING;
	if (kq->kq_refcnt > 1)
		msleep(&kq->kq_refcnt, &kq->kq_lock, PSOCK, "kqclose", 0);

	KASSERT(kq->kq_refcnt == 1, ("other refs are out there!"));

	KASSERT(knlist_empty(&kq->kq_sel.si_note),
	    ("kqueue's knlist not empty"));

	for (i = 0; i < kq->kq_knlistsize; i++) {
		while ((kn = SLIST_FIRST(&kq->kq_knlist[i])) != NULL) {
			if (kn_in_flux(kn)) {
				kq->kq_state |= KQ_FLUXWAIT;
				msleep(kq, &kq->kq_lock, PSOCK, "kqclo1", 0);
				continue;
			}
			kn_enter_flux(kn);
			KQ_UNLOCK(kq);
			knote_drop(kn, td);
			KQ_LOCK(kq);
		}
	}
	if (kq->kq_knhashmask != 0) {
		for (i = 0; i <= kq->kq_knhashmask; i++) {
			while ((kn = SLIST_FIRST(&kq->kq_knhash[i])) != NULL) {
				if (kn_in_flux(kn)) {
					kq->kq_state |= KQ_FLUXWAIT;
					msleep(kq, &kq->kq_lock, PSOCK,
					       "kqclo2", 0);
					continue;
				}
				kn_enter_flux(kn);
				KQ_UNLOCK(kq);
				knote_drop(kn, td);
				KQ_LOCK(kq);
			}
		}
	}

	if ((kq->kq_state & KQ_TASKSCHED) == KQ_TASKSCHED) {
		kq->kq_state |= KQ_TASKDRAIN;
		msleep(&kq->kq_state, &kq->kq_lock, PSOCK, "kqtqdr", 0);
	}

	if ((kq->kq_state & KQ_SEL) == KQ_SEL) {
		selwakeuppri(&kq->kq_sel, PSOCK);
		if (!SEL_WAITING(&kq->kq_sel))
			kq->kq_state &= ~KQ_SEL;